This invention relates to a measuring apparatus such as a radiation thermometer which, for example, receives infrared rays radiated from an object to be measured and measures the temperature of the object based on an amount of received infrared rays.
There have been generally known radiation thermometers which measure the temperature of an object to be measured in an indirect manner by focussing infrared rays radiated from an object to be measured in a specified direction by means of a focussing member such as a lens, and receiving the focused rays by a temperature measuring sensor including a photoelectric conversion element.
There has been proposed a radiation thermometer in which a spot marking device is attached to a temperature measuring optical unit. The spot marking device projects light from a light source onto the object to be measured through a masking element and an objective lens. The position and the distance of the temperature measuring optical unit relative to the object are adjusted until an image made of the light projected from the spot marking device appears sharply focused on the object, thereby confirming a measuring area, and focussing the objective lens. Such a radiation thermometer is disclosed in Japanese Unexamined Patent Publication No. 63-255630.
With this radiation thermometer, the temperature measuring area can be confirmed at a position where the objective lens is focused since the focussing is conducted. However, this radiation thermometer requires adjustment of the optical unit relative to the object in order to focus the objective lens, which is rather cumbersome. Further, the focussing is not easily conducted because a focused state of the light image formed on the object by means of the spot marking device is checked with an operator's eyes. Particularly, in the case where the object itself is bright, it is hard to see the light image, thereby making the focussing and confirmation of the temperature measuring area difficult. These are the problems residing in the above radiation thermometer.
The radiation thermometers are used for inspection and maintenance of apparatuses in a variety of industrial fields because of their capability of measuring the temperature of the object in a position spaced apart from the object. However, to this end, it is required to record what type of apparatus and of which part of the apparatus has been subjected to the temperature measurement. This operation is very cumbersome. As a means to solve this cumbersomeness, it is known that a camera is attached to a backside of the radiation thermometer so as to photograph the object image together with the measurement value.
However, in the above arrangement, an optical axis of the radiation thermometer does not correspond with that of the camera. Accordingly, there are cases where an area of the object measured by the radiation thermometer differs from an area of the object photographed by the camera, thereby presenting a temperature measuring condition imprecisely. In addition, it is difficult to manipulate this arrangement accurately.
It is an object of the invention to provide a measuring apparatus which has overcome the problems residing in the prior art.